Formic Acid Burns Induce Progressive Oxidative Stress and Inflammation: A Pilot Comparative Study with Thermal Burns

Abstract

Background: Formic acid is a corrosive chemical used in industry that may cause severe chemical burns. Contact with this corrosive agent shows a distinct characteristic of thermal burn. This pilot study aimed to investigate whether a short 20–second exposure to formic acid is sufficient to induce skin damage.

Methods: An experimental burn proceeded using porcine as a model. Skin damage following exposure to formic acid for 20 seconds was compared to thermal burn.   Histo-morphological change, inflammatory pathway, and oxidative stress were the variables of interest.

Results: Heated metal exposure caused immediate coagulative necrosis with eschar formation, whereas formic acid exposure led to progressive tissue discoloration and delayed necrosis. Histopathological analysis revealed epidermal disorganization and inflammatory cell infiltration in the formic acid group. NF–κB and HMGB1 expression were significantly increased after formic acid exposure, indicating sustained inflammation. An immediate increase of 8–isoprostane levels peaked 6 hours postburn (heated metal), whereas formic acid led to a gradual but persistent increase of 8–isoprostane.

Conclusion: A short 20–second exposure to formic acid can induce oxidative stress and inflammation in porcine skin, with a delayed but progressive injury pattern distinct from thermal burns. These findings provide forensic and clinical insights into chemical burn pathophysiology, warranting further investigation into long–term effects and therapeutic interventions.